Ultrafine PtFe Alloys Loaded on Three-Dimensional Graphene for Highly Efficient Oxygen Reduction Reaction

A three-dimensional graphene oxide (3DGO) support was synthesized via a formaldehyde-melamine resin-assisted hydrothermal condensation strategy, serving as a framework for the polyol-mediated in situ growth of ultrafine platinum–iron (PtFe) alloy nanoparticles to yield the PtFe/3DGO electrocatalyst. This facilitated a highly uniform dispersion of PtFe alloy particles with an average diameter of 1.87 ± 0.56 nm. XRD and HRTEM results consistently confirmed that Fe incorporation induced pronounced lattice contraction, as evidenced by the reduction in Pt (111) interplanar spacing from 0.226 to 0.219 nm, thereby confirming the formation of a highly alloyed PtFe structure. XPS analysis identified electronic redistribution in Pt 4f orbitals, confirming a downward migration of the d-band center driven by combined ligand and strain effects. The PtFe/3DGO catalyst exhibits exceptional ORR activity in 0.5 M H 2 SO 4 , with an onset potential of 1.1 V (vs. RHE) and a half-wave potential of 0.751 V, yielding a 31-mV positive shift relative to Pt/C. With an initial electrochemical active surface area (ECSA) of 122.2 m 2 ·g −1 Pt , PtFe/3DGO retains 51.2 m 2 ·g −1 Pt after 20,000 accelerated durability test (ADT) cycles, significantly outperforming the stability of Pt/C (which spans only 5000 cycles). This performance enhancement can be largely ascribed to the synergistic effect of three-dimensional spatial confinement and alloy-induced electronic modulation, providing possible insights for the rational design of high-efficiency electrocatalysts.